II.—On the Continuity and Breaks Between the Various Divisions of the Silurian Strata in the Lake District

Extract

In a former communication I stated that the line of division between the Skiddaw Slates and the overlying Volcanic series (Green Slates and Porphyries), in the neighbourhood of Keswick, was a faulted one, and not an unconformity, as supposed by Mr. Dakyns. I added that the evidence of an unconformity (if there was one), between these two series of beds, must be sought for elsewhere than in the district described by Mr. Dakyns. Since then I have examined many miles of boundary between these formations, and have as yet only seen one unfaulted junction, and this is near Bootle, in the Black Combe district, Cumberland; but this section at once sets at rest the question of unconformity or conformity. Not only do the Volcanic series lie at the same inclination with the Skiddaw Slates below them, but beds of the latter alternate with beds of the former, showing a perfect sequence and conformity. When the whole of the boundaries between the Skiddaw Slates and Volcanic series are traced, there may be found other spots also showing conformity and passage.